Simple and efficient protocol for amaranth betalains extraction and stability analysis by ATR-FTIR spectroscopy

Betalains are pigments highly appreciated in the food industry for their applications for human consumption and for their different contributions to human health. However, the stability of betalains is compromised by several factors, including temperature and pH, so it is necessary to determine the optimal conditions to maintain the betalains stability in the final product. In this study, different protocols for extracting betalains from amaranth are compared, and Attenuated Total Reflectance-Fourier Transformation Spectroscopy (ATR-FTIR) together with principal component analysis (PCA) is used to determine amaranth pigments stability at different temperatures and pHs. A simple and efficient method to extract betalains from amaranth plants was established. It was possible to know the stability of amaranth betalains under different temperatures and pH conditions using ATR-FTIR and UV/Vis spectroscopy. The bands associated with carboxylic acids, amino groups, carbon dioxide and carbon double bonds detected by ATR-FTIR spectroscopy were related to the state of conservation and degradation of betalains. Our results will improve the storage, supervision and application of betalains in the food industry. [Display omitted] •We established a fast and efficient protocol for extraction of betalains from amaranth plants.•The stability and dye capacity of betalains were achieved between −20 °C and 22 °C, and pH 4 to 8.•ATR-FTIR result in a fast, practical, and sensitive strategy to study the degradation of betalains.•Our results are important for the preparation of products using the betalains pigments.